1. Field of the Invention
The present invention relates to torque measuring devices, and particularly to a device for measuring torque in the output shaft of a gas 1 turbine engine.
2. Description of the Prior Art
Gas turbine engines having an output shaft may be connected to a gear reduction assembly for driving a propeller or for driving generators and other auxiliary assemblies. It is important to monitor the torque of the output shaft to facilitate power management and to avoid overloading of the engine or transmission system.
Such shaft torque measuring devices are well known and commonly used in the gas turbine engine art with satisfactory results. Most such devices are provided with a single torque tube and a concentric cover which is used as a reference element. The cover is fixed at one end to the torque tube being measured. The other end is free and is provided with an exciter wheel in the form of a gear wheel having teeth which are compared in phase with a similar adjacent gear wheel mounted on the torque tube being measured. Evidently, the greater the linear distance between the fixed connection of the torque tube and cover to the exciter gear wheels, the greater the rotational displacement, under torque loading, there is between the gear teeth, allowing for more accurate torque measurement.
However, the length necessary for such a torque measuring device may, in some cases, be too great for the overall length of the engine, particularly in the design of small turbine engines, such as are used in a helicopter environment.